This invention relates in general to refractory materials and more particularly to a high temperature insulation of a fibrous nature.
Many refractory materials are quite heavy and as a result are unsuitable for aerospace applications. Where they are used, they are often difficult to handle and large foundation structures are usually required. Moreover, most of these heavy refractory materials cannot withstand thermal shock, that is, rapid variations in temperature, for when subjected to rapid temperature variations, tend to crack and spall. Firebrick is an example of such a refractory material.
Due to the foregoing limitations aerospace engineers have turned to so-called ablative materials where extremely high temperatures are encountered, such as during the re-entry of a space craft into the earth's atmosphere. Ablators dissipate heat through pyrolysis and other modes of heat rejection and consequently degrade in use. Generally, ablative materials are used only once, and therefore such materials are not suitable where reuse of the heat shield is desired.